You mentioned NatWest. I remember using NatWest and noticing on NoRoot Firewall (on my Android) it was 'speaking' regularly to Facebook. Of course I had all FB and IG and their IP ranges blocked from the get-go, but still. Why (TF!!!!) would my effing back telling FB that I launched their app? (one could say that they use this or that library, so the code, blah blah blah)
This is disgusting and the reason I don't use iOS. The utter lack of firewall! (plus the batterygate scandal)